This proposal from the University of California, Davis (UCD) and its subcontractor at CHORI seeks to establish and operate the Knock-Out Mouse Program (KOMP) Repository for the purpose of ensuring the preservation, protection, availability, and accessibility of the KOMP resources for use by the scientific research community. The repository will be built upon the closely linked infrastructure, technical support, and faculty expertise within the UCD Mouse Biology Program, Center for Comparative Medicine, the Schools of Medicine and Veterinary Medicine, and the CHORI BACPAC Resource. UCD shall serve as the lead institution and assume administrative oversight, management, and reporting authority and responsibility for all repository activities. UCD shall archive, maintain, QC, and distribute ES cell clones, live mouse lines, and frozen embryos and sperm, while CHORI shall archive, maintain, QC, and distribute all vectors. Our goals will be to 1) to verify the viability, identity, and utility of the collection;2) make finding and ordering all KOMP products and value-added services simple and easy on-line;and 3) distribute KOMP products promptly and for reasonable cost. To achieve these goals, we shall 1) expand 100% of all gene-targeted ES cell lines to 12-15 vials each;2) genotype, karyotype, and pathogen-screen ES cell clones in each shipment;3) reanimate 425 clones to live mice and test for germline transmission of the mutant allele;4) convert 925 mouse lines (~11% of the collection) to a cryopreserved embryo and sperm archive, and 5) confirm the genotype and SPF-status of each clone when ordered. Requesting investigators will have full access to all UCD resources and services, including reanimation of ES cells into live mice, etc. We shall coordinate our relational databases, internally track KOMP products, interface with the Data Coordinating Center, maintain an easily-navigable and informative public website (www.komp.org), and provide an online searchable catalog and ordering system for all KOMP products, services, and related information. We shall provide attentive customer and technical service to respond to telephone (1-888-KOMP-MICE) and email (service@komp.org) requests for information. Products and services will be offered to requesting investigators for a reasonable fee, enabling us to cost recover for distribution and to develop a self supporting repository operation within 4 years.